The technology changes will result in emission reductions, including oxides of nitrogen (NOx), benzene, toluene and xylene (BTX), greenhouse gases and hydrocarbons.
Also included is new equipment designed to change the carbon dioxide absorption process on its existing three LNG processing units in 2004-05, at a cost of more than A$26 million, which includes modifying similar processing systems on its fourth LNG train, which is due for start up in mid-2004.
A further technology improvement - to enhance the combustion of fuel gases in the plant's existing 25 gas turbines - will cost more than A$6 million.
These combined improvements are expected to reduce NOx emissions from the plant by 25% and BTX by up to 75%.
It will also result in a greenhouse gas emission reduction of 350,000 tonnes a year from the facility.
The North West Shelf Venture's Chief Executive, Steve Ollerearnshaw, said the Venture had extensively reviewed its air emissions and reduction options and aimed to move beyond regulatory compliance in line with community expectations.
"These significant reductions will be achieved by changing the process that removes carbon dioxide from natural gas during LNG production," he said.
"This will involve switching to a new carbon dioxide absorption process which will recover an additional 80,000 tonnes of hydrocarbons that would otherwise have been discharged to the atmosphere.
"The Venture will also modify its 25 gas turbines on site which will result in cleaner burning of fuel gases and a subsequent reduction in the NOx emissions from the plant."
Ollerearnshaw said the Venture's greenhouse gas emissions had been reduced by 500,000 tonnes a year since 2001 through a variety of projects.
"The plant has also reduced gas flaring over the past year by 50% and is currently undertaking a major ambient air monitoring program around Karratha and Dampier," he said.
The six equal participants in the North West Shelf Venture are Woodside Energy (operator); BHP Billiton Petroleum (North West Shelf); BP Developments Australia; ChevronTexaco Australia; Japan Australia LNG (MIMI); and Shell Development (Australia).